Antistain agents comprising mixtures of secondary-alkylhydroquinones

ABSTRACT

MIXTURES OF AT LEAST TWO SECONDARYALKYLHYDROQUINONES IN WHICH THERE ARE FROM ONE TO TWO SECONDARY-ALKYL SUBSTITUENTS EACH HAVING HAVING 9 TO 20 CARBON ATOMS AND, PREFERABLY, MIXTURES THAT CONTAIN SECONDARY-ALKYLHYDROQUINONE ISOMERS THAT ARE EUTECTICS WITH LOW EUTECTIC POINTS, I.E., NEAR OR BELOW ROOM TEMPERATURE, ARE PHOTOGRAPHIC ANTISTAIN AGENTS THAT ARE SUPERIOR IN CHEMICAL AND PHYSICAL PROPERTIES TO ANTISTAIN AGENTS DESCRIBED IN THE PRIOR ART. DISPERSIONS OF THE IMMEDIATE ANTISTAIN AGENTS IN HYDROPHILIC COLLOIDS CAN BE HELD BEFORE COATING AT TEMPERATURES BELOW ROOM TEMPERATURE WITHOUT CRYSTALLIZING WHILE ANTISTAIN AGENTS OUTSIDE THE INVENTION DO CRYSTALLIZE.

United Swtes Patent flice 3,700,453 ANTISTAIN AGENTS COMPRISING MIXTURESF SECONDARY-ALKYLHYDROQUINQNES William F. Knechel, Rochester, N.Y.,asslgnor to Eastman Kodak Company, Rochester, N.Y. No Drawing. FiledMar. 6, 1970, Ser. No. 17,330

Int. Cl. G03c 1/76 US. Cl. 96-74 16 Claims ABSTRACT OF THE DISCLOSUREThis invention relates to color photography and particularly tomaterials for preventing the formation of color fog or stain inphotographic emulsions.

The method of color photography in which color forming or couplercompounds combine with the development product of aromatic aminophotographic developers to produce dyes is well known. The color formersor couplers may be added directly to the emulsion layers or may beincorporated in the developing solution as described in Fischer U.S.Pat. 1,102,028, granted June 30, 1914, or they may be incorporated in awater-permeable medium which is insoluble in the carrier for thesensitive silver salt as described in Mannes and Godowsky US. Pat.2,304,940, Dec. 15, 1942, and Jelley and Vittum US. Pat. 2,322,027,granted June 15, 1943.

A difiiculty frequently encountered in these processes is the formationof color fog or stain. When the exposed material is developed in acolor-forming developer, dye fog is frequently formed in the emulsionlayer. This is because the developing agent has been oxidized to someextent by the action of the air and the oxidized developer tends tocouple with the color-forming compound at places in the photographicmaterial where no silver image is produced. It is well known that inthese processes the dye should be formed only where the silver halide isreduced to metallic silver, thereby oxidizing the developing agent to aform which couples with the color former.

Once the developing agent is oxidized, it couples immediately with thecolor former whether a photographic image is present or not. Aerialoxidation of the developer or oxidation by means other than thephotographic image therefore converts the developer to a form which willimmediately react with the color former to produce a color fog or stain.This elfect is especially noticeable in materials halving couplersincorporated in the sensitive layers since there is no coupler in thedeveloping solution to react with any developing agent which is oxidizedby the action of the air. Fog or stain arising from these causes is notreadily controlled by the same procedures used to control silver fog.

The incorporation of hydroquinone or certain of its derivations is wellknown in the prior are for the control of color fog or stain.

The alkyl and di-alkyl hydroquinones available in the prior art havecertain disadvantages however. Many are difiicult to synthesizerequiring two to four steps; others have low molecular weights whichallow them to wander between layers in a multilayer color photographicmaterial, thereby causing undesirable side efliects; still otherscrystallize out during or after coating to give poor coating quality;and also some of the alkyl hydroquinones can be shown to undergo anoxidation reaction during coating operations, or during processing togive colored byproducts.

It is an object of my invention, therefore, to provide novel antistainagents which are easily synthesized.

It is also an object of my invention to provide novel antistain agentswhich do not crystallize from dispersions in aqueous hydrophilic colloidcoating compositions before, during or after coating.

Another object of my invention is to provide novel liquid antioxidantswhich are advantageously incorporated as dispersions in aqueoushydrophilic colloid coating compositions without the use of a solvent.

A further object is to provide novel antistain agents which are notoxidized to colored by-products in aqueous hydrophilic colloid coatingcompositions before, during coating, or during processing.

Another object is to provide novel photographic ele ments containing atleast one hydrophilic colloid layer containing a dispersion of ourantistain agents.

These and other objects of my invention will become apparent from thefollowing description of my invention.

These and still other objects are accomplished accord ing to myinvention by the preparation of my antistain agents which are mixturesof at least two secondary-alkylhydroquinones in which the secondaryalkyl substit-uents have from 9 to 20 carbon atoms, the preparation ofdispersions of my antistain agents in hydrophilic colloids, and the usein multilayer multicolor photographic elements of coatings ofhydrophilic colloid containing dispersions of my antistain agents.

My antistain agents are mixtures of at least twosecondary-alkylhydroquinones which are monosubstituted and/ordisubstituted hydroquinones in which the secondary-alkyl groups havefrom 9 to 20 carbon atoms, such as, a secondary nonyl group (e.g.,l-methyloctyl, l-ethylheptyl, l-propylhexyl, l-butylamyl, etc.), asecondary decyl group (e.g., l-methylnonyl, l-ethyloctyl,l-propylheptyl, l-butylhexyl, etc.), a secondary-undecyl group (e.g.,l-methyldecyl, l-ethylnonyl, l-propyloctyl, l-butylheptyl,l-pentylhexyl, etc.) a secondary-dodecyl group (e.g., l-methylundecyl,l-ethyldecyl, l-propylnonyl, 1- butyloctyl, l-amylheptyl, etc.), asecondary-tridecyl group (e.g., l-methyldodecyl, l-ethylundecyl,l-propyldecyl, 1- butylnonyl, l-amyloctyl, l-hexylheptyl, etc.), asecondary-tetradecyl group (e.g., l-methyltridecyl, l-ethyldodecyl,l-propylundecyl, l-butyldecyl, l-amylnonyl, l-hexyloctyl, etc.), asecondary-pentadecyl group (e.g., l-methyltetradecyl, l-ethyltridecyl,l-propyldodecyl, l-butylundecyl, l-amyldecyl, l-hexylnonyl, etc.), asecondaryhexadecyl group (e.g., l-methylpentadecyl, l-ethyltetradecyl,l-propyltridecyl, l-butyldodecyl, l-amylundecyl, l-hexyldecyl,l-heptylnonyl, etc.), a secondary-heptadecyl group (e.g.,.l-methylhexadecyl, l-ethylpentadecyl, l-propyltetradecyl,l-butyltridecyl, l-amyldodecyl, l-hexylundecyl, l-heptyldecyl,l-octylnonyl, etc.), a secondaryoctadecyl group (e.g.,l-methylheptadecyl, l-ethylhexadecyl, l-propylpentadecyl,l-butyltetradecyl, l-amyltridecyl, l-hexyldodecyl, l-heptylundecyl,l-octyldecyl, etc.), a secondary-nonadecyl group (e.g.,l-methyloctadecyl, l-ethylheptadecyl, l-propylhexadecyl,l-butylpentadecyl, l-amyltetradecyl, l-hexyltridecyl, l-heptyldodecyl,l-octylundecyl, 1-nonyldecyl, etc.) and a secondary-phytyl group (e.g.,l-methylnonadecyl, l-ethyloctadecyl, l-propylheptadecyl,l-butylhexadecyl, l-amylpentadecyl, 1-

Patentecl Oct. 24, 1972' hexyltetradecyl, l-heptyltridecyl,l-octyldodecyl, l-nonylundecyl, etc.

In the simplest mixtures containing two differentsecondary-alkylhydroquinones usually there is in the range from 1% to99% of one compound and in the range from 99% to 1% of the secondcompound. A preferred range is from to 95% of one compound and from 95%to 5% of the second compound. A large variety of mixtures ofsecondary-alkylhydroquinones are used to advantage according to myinvention. For example, (1) mixtures of 2-secondary-alkylhydroquinonesin which the compounds differ in the number and/or arrangement (positionisomers) of carbon atoms in the alkyl group are used to advantage, (2)mixtures of 2,5-di-secondaryalkylhydroquinones in which the compoundsdiffer in the number and/or arrangement of carbon atoms in the alkylgroup on one or both, i.e., 2- and 5-position substituents are used toadvantage, and mixtures of (1) and (2) are used to advantage. Preferredmixtures of my invention are mixtures of isomers of a2-secondary-alkylhydroquinone, mixtures of isomers of a2,5-di-secondary-alkylhydroquinone or mixtures of a2-secondary-alkylhydroquinone (a single compound or mixture of two ormore isomers) and a 2,S-di-secondary-alkylhydroquinone (a singlecompound or mixture of two or more isomers).

Such mixtures of isomers are advantageously made by reactinghydroquinone with the appropriate primary olefin(s) containing from 9 tocarbon atoms in the presence of a Lewis Acid at elevated temperaturesover an extended period of time so that isomeric forms of the primaryolefin are formed and react with hydroquinone to produce at least oneisomeric compound of the monosubstituted secondary-alkylhydroquinone andat least one isomeric compound of the disubstitutedsecondary-alkylhydroqninone compound in a single reaction step. An inertsolvent, preferably immiscible with water, such as, benzene,nitrobenzene, toluene, xylene, etc., is advantageously used for thereaction mixture. Lewis Acids are protons and sources of protons, suchas acids, metal atoms which are able to form coordination systems withwater or ammonia, sulfur from sulfur dioxide, sulfuric acid, sodiumbisulfite, atoms and free radicals with incomplete electron shells, etc.Especially useful Lewis Acids are sulfuric acid, phosphoric acid,hydrochloric acid, sodium bisulfate, monosodium phosphate, zincchloride, aluminum chloride, boron trifiuoride, benzene sulfonic acid,silica-alumina, Amberlite IR-12O (Rohm and Haas Co. trade name for anacidic ion exchange resin), etc. It is advantageous to heat a solventsolution of hydroquinone together with the Lewis Acid to distill anymoisture from the mixture as an azcotrope and then add the primaryolefin or primary olefins while raising the temperature of the reactionmixture to a temperature in the range of from about 130 C. to about 240C. over an extended period of time. The rate at which the olefin isadded to the reaction mixture, the rate of heating and the reaction timeare selected so as to produce the desired mixture of isomers in thefinal product. The most advantageous reaction conditions will dependupon the particular mixture of isomers desired and are readilydetermined. After the reaction is completed, the reaction mixture iscooled, added to a suitable organic solvent such as ligroine; the LewisAcid is removed by filtration or other appropriate means; the unreactedolefin is removed by distillation at reduced pressure and then themixture of my secondaryalkylhydroquinones is distilled off at reducedpressure or separated from the residual reaction mixture by otherappropriate means. The hot mixture of my compounds is advantageouslyprotected from air oxidation whenever possible during this procedure bykeeping it under a nitrogen atmosphere.

The following mixtures of secondary-alkylhydroquinones are illustrativeof those used to advantage as antistain agents according to myinvention.

4 Mixture 1 2-( l-methyloctyl hydroquinone 2,5-di(l-methyloctyl)hydroquinone 2,5 -di l-ethylheptyl hydroquinone 2,5-di(1-propylhexyl)hydroquinone and 2,5-di( l-butylamyl)hydroquinone Mixture2 Mixture 3 Is like Mixture 2, but includes the following additionalcompounds:

2- l-propylnonyl) hydroquinone2-(1-ethyldecyl)-5-(l-propylnonyl)hydroquinone 2-(l-ethyldecyl)-5-(1-amylheptyl)hydroquinone, and 2-( 1-propylnonyl)-5-(l-butyloctyl)hydroquinone Mixture 4 Is like Mixture 2, but contains2-(1-propylnonyl)hydroquinone in place of 2-( l-amylheptyl)hydroquinoneand contains 2-(1-ethyldecyl)-5-(1-propylnonyl)hydroquinone,2-(1-ethyldecyl) 5 l-amylheptyl)hydroquinone, and 2- (l-propylnonyD-S-(lbutyloctyl)hydroquinone in place of2-(1-propylnonyl)-5(l-amylheptyl)hydroquinone and2-(1-butyloctyl)-5-(1-amylheptyl)hydroquinone.

Mixture 5 2-( l-methylundecyl hydroquinone and 2,5 -di-(l-methylundecyl) hydroquinone Mixture 6 2-( l-methylundecyl)hydroquinone 2,5 -di( l-methylundecyl) hydroquinone 2,5-di(l-ethyldecyl) hydroquinone, and

2-(1-methylundecyl)-5-( 1-ethyldecyl)hydroquinone Mixture 7 2-l-methyldecyl hydroquinone and 2,5 -di( l-methyldecyl) hydro quinoneMixture 8 2-( l-methyldodecyl)hydroquinone and 2,5 -di( l-methyldodecyl)hydro quinone Mixture 9 2-( l-methyldodecyl)hydroquinone 2-(l-ethylundecyl)hydroquinone 2,5-di l-methyldodecyl) hydroquinone 2,5 -dil-ethylundecyl hydro quinone 2,5-d1(1-propyldecyl)hydroquinone, and2-(1-methy1dodecyl)-5-(l-ethylundecyl)hydroquinone Mixture 10 2-l-methyltridecyl)hydroquinone and 2,5 -di l-methyltridecyl) hydroquinoneMixture 11 2-( l-methylpentadecyl)hydroquinone and 2,5-d1l-methylpentadecyl hydro quinone Mixture 12 i 2- l-methylnonadecyl)hydroquinone and 2,5-di( l-methylnonadecyl)hydroquinone In addition tothe specific compounds shown in Mixture Nos. 5, 7, 8, 10, 11 and 12, oneor more isomers are advantageously included of either or both the monoordi-substituted secondary-alkylhydroquinone. Mixtures like Mixture 10,for example, can have as many as seven isomers of the monosubstitutedsecondary-alkylhydroquinone and as many as27 isomers of thedisubstituted secondaryalkylhydroquinone. Mixtures like Mixture 12, forexample, can have as many as nine isomers of the monosubstitutedsecondary-alkylhydroquinone and forty-five isomers of the disubstitutedsecondary-alkylhydroquinone.

My mixtures are eutectic mixtures (or nearly eutectic mixtures) in whichthe components produce minimum eutectic points, preferably below roomtemperature.

My mixtures of secondary-alkylhydroquinones are advantageously dispersedin any of the well-known photographic hydrophilic colloids, includinggelatin, albumen, collodion, gum arabic, agar-agar, cellulosederivatives, e.g., alkyl esters of carboxylated cellulose, hydroxyethylcellulose, synthetic resins, e.g., the amphoteric copolymers describedby Claver et al. in US. Pat. 2,949,442, polyvinyl alcohol, polyvinylpyrrolidone, copolymers of an alkyl acrylate, analkylcarbonylacetoxyalkylacrylate and either a sulfoalkylacrylate oracrylic acid, e.g., are described by Smith in US. Pat. 3,488,708, issuedJan. 6, 1970, particularly from line 28 in column 5 to line 8 in column6, and others well known in the art. My mixtures that are liquid at roomtemperature are readily dispersed without the need of a solvent. Mymixtures that are not liquid at room temperature are advantageouslydispersed as a solution in (1) a high-boiling organic crystalloidalsolvent, such as alkyl esters of phthalic acid, e.g., methyl phthalate,ethyl phthalate, prdpyl phthalate, n-butyl phthalate, di-n-butylphthalate, n-amyl phthalate, isoamyl phthalate and dioctyl phthalate,and esters of phosphoric acid, e.g., triphenyl phosphate, tricresylphosphate, diphenyl mono-p-tert, butyl phenyl phosphate or (2)lowboiling organic solvents, such as, lower alkyl acetates, ethylpropionate, sec.-butyl alcohol, methyl isobutyl ketone, ,B-ethoxyethylacetate, methyl Cellosolve acetate, acetonyl acetone, etc.

Dispersions in hydrophilic colloids of my antistain agents( my mixtures)are characterized by not crystallizing when held at temperatures belowroom temperature before, during and after coating as a layer in amultilayer photographic element. This represents a valuable technicaladvance over the prior art antistain agents which do crystallize fromdispersions in hydrophilic colloids while being held below roomtemperature prior to coating.

Dispersions of my antistain agents are further characterized by notproducing discolorations that certain prior art antistain agentsproduce.

Dispersions of my antistain agents in hydrophilic colloids areadvantageously coated in any of the layers of any of the multilayermulticolor photographic elements where antistain agents are used. Forexample, they are advantageously added to one or more of thelight-sensitive layers and/ or in nonlight-sensitive layers coated overor between the light-sensitive layers. They are used in photographicelements that contain incorporated colorforming couplers in thelight-sensitive emulsion layers or in multilayer multicolor photographicelements that do not contain incorporated color-forming couplers. Thephotographic elements are either of camera speed or elements such as areused for reflection color prints. The elements are coated on any of theusual support materials such as paper, other fibrous support, celluloseacetate or any of the synthetic polymers used for photographic filmsupports. My antistain agents are dispersed in hydrophilic colloids inthe range of from about 01% to about 90%, by weight, of dry hydrophiliccolloid and, preferably, in

the range from about 1% to about The optimum concentration will dependupon the particular photographic element in which my antistain agentsare to be used and is easily determined by methods well known in theart.

My antistain agents actively reduce the oxidized form of any of theprimary aromatic amine color-developing agents (used in color processes)back to the developing agent or to a form that will not couple withcolor-forming coupler. Hydrophilic colloid layers of my antistain agentscoated between two light-sensitive layers are very effective inpreventing oxidized color developing agent formed by development in onelight-sensitive layer from wandering into the second layer and formingunwanted dye in the second layer.

In the prior art, the pure compounds used as antistain agents, such as2,5-di-n-d0decylhydroquinone required four steps in its synthesis andthe pure 2-n-dodecylhydroquinone required two steps. By use of myinvention, only a one-step synthesis is required, and an antistain agentis obtained which is superior in its chemical and physical properties toany described in the prior art.

The following examples are included for a further understanding of myinvention.

EXAMPLE 1 (A) Pure 2,S-di-n-dodecylhydroquinone (not of my in vention),designated as Antistain Agent X, is prepared as described in lines48-68, column 8 of US. Pat. 2,728,659, Loria et al., using four reactionsteps (M.P. 108l 10 C.)

(B) The mixed isomers of secondary-dodecylhydroquinone are preparedusing my invention as follows: In a 500-ml. 4-necked flask, in an oilbath, equipped with a stirrer, distillation head, dropping funnel andthermometer, are placed 55 g. (0.5 mole) of hydroquinone, 18 g. of asilica-alumina catalyst, and ml. of toluene. While stirring, thereaction mixture is heated in the oil bath, and the toluene-waterazeotrope is removed. When about 75 ml. is collected, the pottemperature is about C. To the hot reaction mixture is added ml. (123g., 0.675 mole) of l-dodecene. The oil bath temperature is raised to 230C., and the reaction temperature rises to 220 C. over a two-hour period.After the temperature of 220-225 C. has been maintained for one hour, anadditional 100 ml. (75 g., 0.446 mole) of l-dodecene is added dropwiseat such a rate that the reaction mixture temperature is not lowered.After stirring at this temperature for an additional three hours, thestirring is stopped and the flask is removed from the oil bath. From nowon the crude product is kept under a nitrogen atmosphere wheneverpossible to prevent oxidation. When this reaction mixture has cooled to120 C., it is cautiously poured into 500 ml. of ligroine. Thesilica-alumina catalyst is removed by filtration and washed withligroine. The ligroine is distilled from the product at atmosphericpressure. The unreacted dodecene is removed by distillation at reducedpressure, collecting the fraction which boils at 781l0/l0 mm. Theproduct is distilled at oil pump vacuum, collecting the fraction whichboils at 210-250/ 0.15 mm. The yield is g. which is 83% of thetheoretical amount of 226 g. based on the amount of hydroquinone used.This mixture of isomers, identified as Antistain Agent A, is a liquid atroom temperature. Gas chro matography shows -that it is a mixture oftwelve of the fifteen possible disubstituted isomers (95% by Weight) andfour of the five possible mono-substituted isomers (5% by weight).

(C) Dispersions are made of Antistain Agents A and X with the followingcompositions:

50 g. antistain agent 25 g. tricresyl phosphate 60 g. gelatin dissolvedin 600 ml. water The melts containing A and X, respectively, are coatedimmediately at rates of 600 rug/ft. of gelatin. Compound X is seen tocrystallize immediately when the coating is examined in cross-sectionphotomicrographs. The dispersions containing Antistain Agents A and Xare held for two hours at 105 F. as melts and then examined forcrystals. Only the dispersion containing Antistain Agent X crystallizes.Also upon holding, the dispersion of Antistain Agent X turns blue due tooxidation of the hydroquinone to a colored quinhydrone. In U.S. Pat.2,728,659 cited herein, Antistain Agent X is described as being animprovement over the prior art in its resistance to oxidation. Thisexample demonstrates that a mixture of isomers of similar structure issuperior to Antistain Agent X in its resistance to oxidation.

EXAMPLE 2 Antistain Agent Y, i.e., 2,5 -di-tertiaryoctylhydroquinone(outside my invention) is compared with Antistain Agent A prepared inExample 1(B). Two dispersions are made as follows:

(1) A solution is made of 40 g. of Antistain Agent Y in g. of tri-cresylphosphate and this is dispersed in 1 l. of aqueous gelatin containing 8%gelatin;

(2) A solution is made of 40 g. of Antistain Agent A in 20 g. oftri-cresyl phosphate and this is dispersed in 1 l. of aqueous gelatincontaining 8% gelatin.

These dispersions are kept at F. and 45% RH for two weeks. Thedispersion containing Antistain Agent Y crystallizes. To demonstrate theinferior quality of dispersion of Antistain Agent Y, the dispersion ismelted and filtered and a quantity of crystallized Antistain Agent Yremains on the filter. This results in the final melt having anincorrect composition. A melt containing a fresh dispersion of AntistainAgent Y is added to the melt containing the crystalline dispersion ofAntistain Agent Y. It is observed that the total melt crystallizesduring holding. The crystals seed the good melt and crystals formedthroughout the good dispersion. No crystals form in the dispersion ofAntistain Agent A (using my invention) and the melt passes completelythrough the filter.

EXAMPLE 3 Three paper-supported multilayer gelatinous silver halidecoatings of the compositions illustrated below are exposed to agraduated-density test object, color developed, bleached, fixed, washedand dried.

Coating No. 1

Like Coating No. 1, but 26 mg./ft. of Antistain Agent X in Layer #2dispersed as in Example 2.

Coating No. 3

Like Coating No. 1, but 26 mg./ft. of Antistain Agent A in Layer #2dispersed as in Example 2.

The effectiveness of Antistain Agents A and X are determined bymeasuring the amount of cyan dye formed in Layer 3 resulting from theinteraction of oxidized color developer from Layer 1 with the coupler inLayer 3. The results are as follows:

. Cyan dye Coating number Antistain agent density 1 None .95 2 X .64 3 A.42

This shows that Antistain Agent A of my invention is substantiallysuperior to Antistain Agent X of the prior art in its antistainproperties. The cyan-dye-forming coupler used in Layer 3 of Coating Nos.1, 2 and 3 is a coupler of the type described in lines 39 through 54 incolumn 2 of Fierke et al., U.S. Pat. 2,801,171, issued July 30, 1957.The yellow-dye-forming coupler used in Layer 1 of Coating Nos. 1, 2 and3 is an a-pivalyl acetanilide coupler of the type described in column 5,line 20, all of column 6 and column 7 through line 4 of Weissberger andKibler, U.S. Pat. 3,265,506, issued Aug. 9, 1966. The silver halideemulsion used in Coating Nos. 1, 2 and 3 is a silver bromoiodideemulsion. The color developer, bleach and fix solutions used in theimmediate example have the composition indicated below:

Color developer solution Water to 1 l.

*4 am1n0-N-ethyl-N-(fl-methanesulfonamldoethyl)-m-toluldinesesqulsulfate monohydrate.

Bleach solution G. Sodium nitrate 45.0 Potassium ferricyanide 22.5Potassium bromide 8.2 Boric acid 7.5

Borax 0.97 Water to 1.0 1.

Fix solution G. Sodium thiosulfate 223.0 Sodium bisulfite 12.0 Sodiumacetate, anhydrous 14.0 Sodium citrate 1.7 Boric acid 5.0 Potassiumalum, granular 24.0

Water to 1.0 1.

EXAMPLE 4 A dispersion is made by passing a mixture of 50 g. ofAntistain Agent A and 60 g. of gelatin in 600 ml. of water through acolloid mill three times. This, when compared to dispersions of Example1, is about 19% lighter in weight. The liquid antistain agent requiresno additional solvent to make a good dispersion. In photographic tests,this dispersion is shown to be substantially identical to a similardispersion in solvent.

Example 1(C) is repeated using equivalent amounts of collodion,agar-agar, hydroxyethyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone and copoly(methylacrylatesodium 3acryloyloxy-l-methylpropane-l-sulfonate-Z- acetoacetoxyethyl acrylate)in place of gelatin. The superior characteristics of my Antistain AgentA over Antistain Agent X are again demonstrated.

EXAMPLE 5 Two multilayer color Elements X and A having a support coatedin succession with a red-sensitized, gelatinous silver bromoiodideemulsion layer, a gelatin layer, a green-sensitized, gelatinous silverbromoiodide emulsion layer, a gelatin layer containing a bleachableyellowcolored dye and a blue-sensitive, gelatinous silver bromoiodideemulsion layer are made like the elements described in FIG. 2 in thedrawing and in the specification on pages 1 and 2 of Mannes et al., U.S.Pat. 2,252,718, issued Aug. 19, 1941, except that the gelatin layersbetween the lightsensitive layers contain a dispersion of an antistainagent. The antistain agent containing layers of Element X (outside myinvention) are coated with the dispersion of Antistain Agent X describedin immediate Examples 1(A) and 1(C). Antistain Agent X is found tocrystallize in the dispersion before coating, during the coatingoperation and after coating, resulting in coating imperfections and someproduct that is unusable. The antistain agent containing layers ofElement A or my invention are coated with the dispersion of AntistainAgent A described in immediate Examples 1(B) and 1(C). Antistain Agent Ais found not to crystallize before, during or after coating Element A.Element A is free of coating defects and is a product that is superiorto Element X. Pieces of Element X and Element A are image exposed andprocessed as described in U.S. Pat. 2,252,718 from page 1, column 2,line 48 through page 2, line 73. Although processed Element X has c'yandye stain in the magenta image layer, Element A is free of cyan dyestain.

EXAMPLE 6 Two multilayer color Elements Z and B like the elementdescribed in Example 2, column 7, line 56 through line 28 in column 8 ofa Van Campen, U.S., Pat. 2,956,879, issued Oct. 18, 1960, having asupport coated in succession with (1) a blue-sensitive gelatino-silverchlorobromide emulsion layer containing a yellow-dye-forming coupler andan antistain agent, (2) a gelatin layer, (3) a green-sensitizedgelatino-silver chlorobromide emulsion layer containing an antistainagent, (4) a gelatin layer containing an ultraviolet-absorbing compoundand an antistain agent and (5) a red-sensitized gelatino-silverbromoiodide emulsion layer containing an antistain agent. These elementsare identical to those described in Example 2 of the cited reference,except that in Element Z a dispersion of Antistain Agent X, as describedin immediate Examples 1(A) and 1(C), is used as the antistain agent ineach of the layers containing an antistain agent. Crystallization ofAntistain Agent X from the dispersion before, during and after coatingElement Z results in coating defects and some product that cannot beused. Element B is like .Element Z, except that a dispersion ofAntistain Agent A,

described in Examples 1(B) and 1(C) of this application, is used as theantistain agent in place of the dispersion of Antistain Agent X in eachof the layers containing an antistain agent. No crystallization ofAntistain Agent A is noticed in the coating compositions before, duringor after coating Element B. Pieces of Elements Z and B are image exposedand color processed with color development, stop, fix, bleach, hardenerfix, etc. as described in column 5, lines 35 through 44 in column '6 ofU.S. Pat. 2,956,879 cited herein earlier. Element B of my inventiongives quality that is superior to Element Z outside my invention.

Similarly, it can be shown that other multilayer multicolor elementscoated With dispersions of my antistain agents are superior to elementscoated with antistain agents outside my invention.

Examples 2, 3, 5 and 6 are repeated using equivalent amounts ofcollodion, agar-agar, hydroxyethyl cellulose, polyvinyl alcohol,polyvinyl pyrrolidone and copoly(methyl acrylate-sodium3-acryloyloxy-l-methylpropane-l-sulfonate-2-acetoacetoxyethyl acrylate)in place of gelatin. Results similar to those shown in Examples 2, 3, 5and 6, respectively, are obtained.

Antistain Agent B of my invention is a mixture of isomers of2-secondary-nonylhydroquinone and of 2,5-di-secondary-nonylhydroquinoneprepared by a procedure like that used to prepare Antistain Agent Adescribed in Example 1(B), but by substituting :an equimolar amount ofl-nonene in place of l-dodecene, and by using nitrobenzene as thesolvent in place of toluene.

Antistain Agent C of my invention is a mixture of isomers of2-secondary-hexadecylhydroquinone and of 2,S-di-secondary-hexadecylhydroquinone prepared by a procedure like thatused to produce Antistain Agent A in Example 1(B) but by substituting anequimolar amount of l-hexadecene in place of 1-dodecene.

A comparison of Antistain Agents B and C of my invention againstAntistain Agent X when dispersed in gelatin as described in Example 1(C)again shows the superiority of my antistain agents over prior artAntistain Agent X. Similarly, it can be shown that Antistain Agent B issubstantially superior to pure 2-secondary-nonylhydroquinone andsubstantially superior to pure 2,5-di-sec ondary-nonylhydroquinone. Itcan also be shown that Antistain Agent C is substantially superior topure 2-sec- 0ndary-hexadecylhydroquinone and is substantially superiorto pure 2,5-di-secondary-hexadecylhydroquinone.

My antistain agents are valuable for incorporation in photographichydrophilic colloid compositions because they are superior to antistainagents outside my invention. For example, dispersions of my antistainagents in hydrophilic colloid can be held prior to coating withoutcrystallizing as do antistain agents outside my invention. My antistainagents are eutectic mixtures (or nearly eutectic mixtures) which havelow eutectic points, preferably below room temperature. Solutions of myantistain agents in conventional high-boiling solvents or conventionallow-boiling solvents are advantageously dispersed in an aqueoushydrophilic colloid. My liquid antistain agents, however, areadvantageously dispersed without solvent in an aqueous hydrophiliccolloid. My antistain agents do not form quinhydrone type dyes that someantistain agents outside my invention form. The antistain agents of myinvention are used very effectively in photographic elements to preventthe wandering of oxidized color developing agents into layers where theycause unwanted dye formation (from coupling reactions). My antistainagents are easily made by a one-step chemical reaction, instead of thetwoor four-step reaction required by prior art compounds.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be eifected within the spirit and scopeof the invention.

I claim:

1. A dispersion in a hydrophilic colloid of a photographic antistainagent that is a mixture of at least two secondary-alkylhydroquinones inwhich the secondaryalkyl substituents have from 9 to 20 carbon atoms,such that said dispersed antistain agent does not crystallize when heldat temperatures below room temperature.

2. A dispersion of claim 1 in which said hydroquinones have from one totwo secondary-alkyl substituents.

3. A dispersion of claim 1 in which said hydrophilic colloid is gelatin.

4. A dispersion in a hydrophilic colloid of a photo graphic antistainagent that is a mixture of at least two secondary-alkylhydroquinoneisomers in which the secondary-alkyl substituents have from 9 to 20carbon atoms, such that said dispersed antistain agent does notcrystallize when held at temperatures below room temperature.

5. A dispersion in a hydrophilic colloid of a nondiffusible photographicantistain agent that is a mixture of at least twosecondary-dodecylhydroquinones, such that said dispersed antistain agentdoes not crystallize when held at temperatures below room temperature.

6. A dispersion of claim 5 in which the hydrophilic colloid is gelatin.

7. A dispersion in a hydrophilic colloid of a nondiffusible photographicantistain agent that is a mixture of secondary-dodecylhydroquinoneisomers that does not crystallize when held at temperatures below roomtemperature.

8. A dispersion in a hydrophilic colloid of a nondiffusible photographicantistain agent that is a mixture of secondary-alkylhydroquinonescontaining:

(1) at least one mono-secondary-dodecylhydroquinone withsecondary-dodecyl substituents selected from the class consisting ofl-methylundecyl, l-ethyldecyl, 1- propylnonyl, l-butyloctyl andl-amylheptyl; and

(2) at least one 2,5-secondary-dodecylhydroquinone withsecondary-dodecyl substituents selected from 11 the class consisting ofl-methylundecyl, l-ethyldecyl, l-propylnonyl, l-butyloctyl andl-amylheptyl.

9. A dispersion in gelatin of a nondilfusible, photographic antistainagent that is a mixture containing:

(1) four mono-secondary-dodecylhydroquinone isomers with substituentsselected from the class consisting of l-methylundecyl, l-ethyldecyl,l-propylnonyl, 1- butyloctyl and l-amylheptyl; and

(2) twelve 2,5 di-secondary dodecylhydroquinone isomers withsubstituents selected from the class consisting of l-methylundecyl,l-ethyldecyl, l-propylnonyl, l-butyloctyl and l-amylheptyl.

10. In a multilayer color photographic element containing hydrophiliccolloid layers containing diiferently sensitized silver halide emulsionsin which the color images are formed during color processing by thereaction of an oxidized primary aromatic amine color developing agentwith color-forming couplers, said element containing at least onehydrophilic colloid layer containing a dispersion of a non-ditfusibleantistain agent, the improvement comprising the use of a nondilfusibleantistain agent that is a mixture of at least twosecondary-alkylhydroquinones in which the secondary-alkyl substituentshave from 9 to 20 carbon atoms.

11. In a multilayer color photographic element containing hydrophiliccolloid layers containing differently sensitized silver halide emulsionsin which the color images are formed during color processing by thereaction of an oxidized primary aromatic amine color developing agentWith color-forming couplers, said element containing at least onehydrophilic colloid layer containing a dispersion of a nondiffusibleantitstain agent, the improvement comprising the use of a nondiifusibleantistain agent that is a mixture of at least twosecondary-alkylhydroquinone isomers in which the secondary-alkylsubstituents have from 9 to 20 carbon atoms.

12. In a multilayer color photographic element containing hydrophiliccolloid layers containing differently sensitized silver halide emulsionsin which the color images are formed during color processing by thereaction of an oxidized primary aromatic amine color developing agentwith color-forming couplers, said element containing at least onehydrophilic colloid layer containing a dispersion of a nonditfusibleantistain agent, the improvement comprising the use of a nondilfusibleantistain agent that is a mixture of at least twosecondary-dedocylhydroquinones.

13. In a multilayer color photographic element containing hydrophiliccolloid layers containing differently sensitized silver halide emulsionsin which the color images are formed during color processing by thereaction of an oxidized primary aromatic amine color developing agentwith color-forming couplers, said element containing at least onehydrophilic colloid layer containing a dispersion of a nondiffusibleantistain agent the improvement comprising the use of a nondiffusibleantistain agent that is a mixture of secondary-dodecylhydroquinonescontaining:

(1) at least two mono-secondary-dodecylhydroquinone isomers withsecondary-dodecyl substituents selected from the class consisting ofl-methylundecyl, l-ethyldecyl, l-propylnonyl, l-butyloctyl andl-amylheptyl; and

(2) at least two di-secondary-dodecylhydroquinone isomers withsecondary-dodecyl substituents selected from the class consisting ofl-methylundecyl, l-ethyldecyl, l-propylnonyl, l-butyloctyl andl-amylheptyl.

14. A dispersion of claim 4 in which the hydrophilic colloid is gelatin.

15. A dispersion of claim 7 in which the hydrophilic colloid is gelatin.

16. In a multilayer color photographic element containing hydrophiliccolloid layers containing dilferently sensitized silver halide emulsionsin which the color images are formed during color processing by thereaction of an oxidized primary aromatic amine color developing agentwith color-forming couplers, said element containing at least onehydrophilic colloid layer containing a dispersion of a nondiifusibleantistain agent, the improvement comprising the use of a nondiffusibleantistain agent that is a isomeric mixture of at least twosecondarydodecylhydroquinones.

References Cited UNITED STATES PATENTS 2,701,197 2/1955 Thirtle 96562,728,659 12/1955 Loria 9656 2,732,300 1/1956 Thirtle 9656 3,022,1672/1962 Green 9656 UX 3,212,893 10/1965 Salrninen 9656 3,243,294 3/1966Barr 9674 2,388,887 11/1945 Weissberger 260625 2,455,746 12/1948Erickson 260625 3,424,821 1/ 1969 Hunter 260625 NORMAN G. TORCHIN,Primary Examiner I. R. HIGHTOWER, Assistant Examiner US. Cl. X.R.106-125; 9656

